Decline in cognitive function is a strong predictor of subsequent dementia and is an important health issue in older adults, whose numbers will burgeon in coming decades. Among potential risk factors for cognitive decline that can be modified-by both individuals and regulations-are exposures to environmental toxins. In particular, indirect evidence suggests that chronic exposure to air pollution may be associated with cognitive decline. In autopsy studies of dogs and humans, air pollution exposure is associated with Alzheimer-like changes in the brain. Moreover, abundant data describe the association of exposure to particulate air pollution-particles suspended in the air-with cardiovascular disease (CVD), while many risk factors for CVD also appear related to cognitive decline. Yet, little is known about the direct relation of air pollution to cognitive decline. Such an association may be especially pertinent to women, who carry a greater lifetime risk than men of cognitive impairments and who appear to be disproportionately susceptible to the health effects of air pollution. Therefore, we propose to conduct an exploratory epidemiologic study of air pollution exposure in relation to cognitive decline among older women. This study, a unique collaboration of the of aging and environmental health disciplines, will capitalize on available data from the Nurses'Health Study (NHS), a large prospective cohort of women followed since 1976. Specifically, beginning in 1995, cognitive function has been assessed via a validated telephone interview among the 20,000 oldest participants (aged 70-81), with serial assessments occurring every 1.5 years after. The test battery assesses general cognitive status, verbal memory, executive function, processing speed, and working memory. Exposures to thoracic (PM10) and fine (PM2.5) particulate air pollution from 1999-2002 have been estimated for the contiguous United States (US) region. For the proposed project, we will extend these PM models back to 1988, and for each woman, we will estimate her average PM exposures over the interval from 1988 to the time of her first cognitive assessment. We will also examine exposure to traffic-generated particles, using both a detailed model of exposure in greater Boston, MA and a more general model for women living in the contiguous US. We will evaluate whether long-term exposure to each of the 3 air pollutants-thoracic, fine and traffic particles-is related to cognitive decline among older women. Using the R21 mechanism, this exploratory project innovatively uses air particulate exposure models, based on geographic information systems (GIS), with telephone cognitive assessments to explore the new area of air pollution and cognitive aging in a large cohort of women. This project will generate important evidence on the plausibility of a relation between long-term exposure to particulate air pollution and cognitive aging, and the data from this project will stimulate further work to confirm and elaborate any associations found, including evaluations of dementia risk and evaluations of other common air pollutants (e.g., ozone). PUBLIC HEALTH RELEVANCE: Decline in cognitive function is an important health issue in older adults and strongly predicts whether an individual will eventually develop dementia. Preliminary evidence suggests that exposure to air pollution may be related to cognitive decline, particularly among older women, and our project, entitled "Air Pollution and Cognitive Aging among Older Women," evaluates this relation in a large population of older women. Since exposure to air pollution is a potential risk factor for cognitive decline that can be modified-by regulations and individual behaviors-our findings, along with further confirmatory data, may offer potential direction for reducing the risk of cognitive decline among a large high-risk population.